Box of Rock variant, with minor changes to cap values Q2/3 source resistors and D-G bias resistor of Q3 so would be quite possible to do a BoR/'59 Sound mode switch with a 4P3T rotary.

I like this more than i remember liking the BoR when i made one years ago, but i just don't like having a single BMP style tilt tone pot and am considering putting a Bassman tonestack on the end instead - If anyone has any advice/suggestions/experience of doing this, feel free to chip in.

brownwhopping wrote:How can I learn by reading threads an making circuits, when some day I can see a lawsuit or somebody beat me in the face for that?

I like this one a lot better than the BoR too. For a bass control I used IVIark's suggestion and swapped the 470K resistor in parallel with the 470pF cap on the base of Q2 for a 1M pot. It's not perfect but it works. It works better at cutting the bass than boosting it, but there's already plenty of low end in the circuit anyway. I used a linear pot and strangely enough 12.00 (approx 470K) seems to sound best to me!

In both stock version and modded version I would like a hair more midrange. If I could get a tiny bit more midrange in there this would be one of my favourite pedals - as it is it's very cool. Fantastic overdrive with a Gibson.

HamishR wrote:...In both stock version and modded version I would like a hair more midrange. If I could get a tiny bit more midrange in there this would be one of my favourite pedals - as it is it's very cool. Fantastic overdrive with a Gibson.

Try increasing the value of the 470p cap. 1n or 2.2n will make the mids more aggressive (in Marshall amps atleast)

Nocentelli: Possibly something like this? The BMP-tone is replaced with a stock Fender stack from Tonestack calc and followed by a recovery stage (as the stack takes more than 10db away) before the output filtering.

If i'm correct, this would make a decent fender amp emulation / drive pedal.

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That's a really interesting idea. That tonestack is more BF era Fender though - I would be more inclined to try a tweed style tone stack, which would use two 22n caps and a 250pF treble cap and a 56K slope resistor. Even though the 5F6-A Bassman schematic shows a .1uF and a .047uF cap in the tonestack they more often came with a pair of .022s. (And that's the tonestack Marshall initially adopted)

Thanks for the tip on the cap - I will try that. And I think Mirosol may be onto something. The stock pedal circuit sounds very good indeed so could be worth experimenting with.

Hey Mr BMX - I removed the 470pF in parallel with the 470K resistor (which is actually a 1M pot in my latest version) and man - you have created a monster! I replaced the 470pF with a 2n2 and it's incredible. It has to be the most authentically JMP Marshall sound I have heard from a pedal. Wow. It is so much better than a Distortron it's crazy.

I guess if i was diligent I should put that cap on a switch so I can choose between 470pF (flatter mids, more '59 Bassman sounds) and the 2n2 (raucous old-school Marshall mayhem). But I think I'll just leave it as 2n2. I have a stock '59 Sound to compare it to and I really like both. I do think Z Vex should stick that cap on a switch because I reckon plenty of players would LOVE the 2n2 cap sound.

It would even be cool as a stomp switch boost. The stock '59 Sound is such a great rhythm sound that being able to switch to the 2n2 would be a handy lead boost option. What I especially like is that the lows are still super punchy and tight. No mush and fuzz there. This pedal and P90s are a wonderful mix...